Method for preparing polychlorotrifluoroethylene resin

Abstract

The invention discloses a method for preparing polychlorotrifluoroethylene resin. The method includes: using CTFE (chlorotrifluor ethylene) as monomer, using mixture of deionized water with perfluor-4-methyl-2-pentane as media, and using perfluor-amyl-butyl peroxide initiator for polymerization of chlorotrifluoroethylene at the temperature of 0-70 DEG C in the existence of fluorine-contained decyl-acrylic acid dibutyl ester surfactant, wherein the feeding amount of the CTFE is 10-40 of the weight of the mixed media, the mass ratio of the deionized water to the perfluor-4-methyl-2-pentane is 2-5:1, usage of the perfluor-amyl-butyl peroxide initiator is 0.1-2% of the weight of CTFE, and usage of the fluorine-contained decyl-acrylic acid dibutyl ester surfactant is normally 0.02-2% of the weight of CTFE. The method is short in polymerization time and high in conversion rate, the obtained polymer is not easy to degrade, deteriorate in performance and discolor at high temperature.

Description

technical field [0001] The invention relates to a preparation method of polychlorotrifluoroethylene resin, belonging to the technical field of preparation of fluorine-containing polymer materials. Background technique [0002] PCTFE is a high value-added, high-performance thermoplastic. As a high-end product, it is often used in harsh environments where other materials cannot be used. When in contact with liquid oxygen, liquid nitrogen and liquefied natural gas, PCTFE has outstanding anti-brittle properties, excellent gas barrier characteristics, and is not affected by ultraviolet and gamma ray radiation. Among refrigerants, PCTFE has outstanding creep resistance characteristics, so it can be used for load bearing parts contacting refrigerant. [0003] PCTFE can be processed by common processes such as injection molding, extrusion, molding and transfer molding. PCTFE is mainly used to make parts of ultra-cold refrigeration equipment, valves (valve seats, valve stems, seal...

AI Technical Summary

Problems solved by technology

[0005] PCTFE is polymerized from chlorotrifluoroethylene (CTFE) as a raw material. In order to obtain PCTFE with sufficient molecular weight to meet the needs of practical applications, a redox initiator system is usually used to polymerize at a lower temperature. The oxidant of the initiator system is generally It is persulfate or organic peroxide, and the reducing agent is sodium bisulfite and sodium metabisulfite. The actual polymerization reaction takes a long time, often exceeding 30 hours, and the conversion rate of chlorotrifluoroethylene is relatively low. The obtained PCTFE Despite its high molecular weight, there are unstable end groups on the molecular chain, which are easily degraded at high temperatures, resulting in poor performance and severe discoloration

[0006] U.S. Patents US2613202, US2689241, and US5453477 add transition metal ions as accelerators in the redox initiation system to shorten the polymerization reaction time, but the actual polymerization time still reaches 20 hours, and the introduction of transition metal ions further aggravates the degradation of PCTFE at high temperatures

[0007] U.S. patents US2751376, US2902477, and US3045000 use solvent-strong oxidant, ozone, and chlorine to treat PCTFE powder, which can significantly improve the high temperature resistance of PCTFE. However, these treatment processes are difficult to apply industrially and cause serious pollution

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